[Null0Naru]

Hi,

Still chasing down some weird performance issues and codes on a 2011 335i.

I'm getting the below codes:

Active:
29D0 - Intake air temperature sensor, electrical: Short circuit to B+

Shadow:
290A - Intake air temperature sensor: Multiple fault.

I'm running MHD Stage 2+. The car feels a bit sluggish and juttery under partial load, but then seems fine at WOT. RPM also dips to around 400rpm sometimes when coasting to a stop. No CEL present.

Does anyone know if these codes are for the MAF sensor in the intake or does it relate to the MAP in the CP or manifold? I've had charge pressure and intake pipe pressure faults before that haven't come back since I replaced the CP MAP sensor with the 3.5Bar N20 sensor.

If I reset the Intake mass flow adaptation, the issue goes away for a little bit but will eventually return. From my understanding, partial load uses the MAF and MAP sensors while WOT only uses MAP. If so, this would make the MAF the main suspect. I want to be sure though, as the MAF sensor is around £300 to replace, so don't want to replace it if the code is for another sensor. The fact that there are other codes which specifically mention the Mass air flow sensor makes be doubtful too.

Any help is appreciated.

[Tunafish]

Its the MAF sensor after air filter. It has a flow sensor and temp sensor. Code 29E0 would be the MAP sensor..

[Null0Naru]

Originally Posted by Tunafish

Its the MAF sensor after air filter. It has a flow sensor and temp sensor. Code 29E0 would be the MAP sensor..

Thanks.

Looking back at my code logs, I've had 29E0 before, but not since I replaced the sensor with the 3.5 Bar one. I wouldn't be surprised if that one went when the stock charge pipe blew.

I'll give the MAF another clean with MAF cleaner today as I'm thinking of moving back to the stock intake anyway. If it doesn't help, I guess it's either £300 from BMW or £200 for a Lexmark or VDO sensor.

[VXEric]

Check your MAF and boost sensor connections for corrosion. My 335 had idle issues and high rpm AFR issues at random for months. They slowly got more common then I started having really low idle that would stall. Finally got to the point of misfires at idle.

Spent weeks trying to chase it down via tuning, smoke tests, and replacing sensors until finally the sensor to B+ short code showed up and it clicked. Sure enough the plug on my boost pressure sensor connector had gotten wet and the smallest spot of corrosion formed. I brushed it out, applied no-ox-id grease to the pins and it's back to running amazingly. I had slowly been losing performance for months, now it feels like a new car.

[Null0Naru]

Originally Posted by VXEric

Check your MAF and boost sensor connections for corrosion. My 335 had idle issues and high rpm AFR issues at random for months. They slowly got more common then I started having really low idle that would stall. Finally got to the point of misfires at idle.

Spent weeks trying to chase it down via tuning, smoke tests, and replacing sensors until finally the sensor to B+ short code showed up and it clicked. Sure enough the plug on my boost pressure sensor connector had gotten wet and the smallest spot of corrosion formed. I brushed it out, applied no-ox-id grease to the pins and it's back to running amazingly. I had slowly been losing performance for months, now it feels like a new car.

Thank you for the suggestion.

I had a look at the connectors while cleaning the MAF and they didn't seem dirty or corroded. The code hasn't come back yet. If it does, I'll give the connectors a clean and see if it helps.

Car's still running a little unusually at low speed and RPM but will take a while for it to re-adjust I suppose.

[anjuna]

upload a log

additionally, you can completely disconnect the MAF - if the MAF is giving off incorrect readings, the DME takes them in to account. If the MAF is disconnected, there are no erroneous readings to consider.

Originally Posted by Null0Naru

Thank you for the suggestion.

I had a look at the connectors while cleaning the MAF and they didn't seem dirty or corroded. The code hasn't come back yet. If it does, I'll give the connectors a clean and see if it helps.

Car's still running a little unusually at low speed and RPM but will take a while for it to re-adjust I suppose.

[Null0Naru]

Originally Posted by anjuna

upload a log

additionally, you can completely disconnect the MAF - if the MAF is giving off incorrect readings, the DME takes them in to account. If the MAF is disconnected, there are no erroneous readings to consider.

That's something I've considered doing at some point to see if it helps, seeing as resetting the air mass adaptation helps.

I actually took it out for another drive tonight and it definitely seems to be getting better. 2nd is still a little off at low RPM, but 3rd is much smoother and feels like the torque is back, where it used to take quite a while for it to kick in.

I've been using the BMS intake with an oiled filter for the last year or so, so wonder if the MAF got some oil on it and the cleaning helped. I've also switched back to the stock airbox as I can't feel any difference between the two and I have heard that open intakes seem to cause some issues on the N55.

I'm going to keep an eye on it for now and see if it keeps improving as it adapts. I'm checking for the code after each drive but nothing's come up yet.

[Null0Naru]

Further update:

Code's still not come back up and the low end torque seems to be back for the most part, the car is driving much better now. Just picked up a new air filter as the one from my stock intake had been sitting in a dirty garage for about a year.

Oil change and other maintenance stuff soon, so I'll keep an eye on it for now, but seems like another clean of the MAF may have fixed the issue.

[Null0Naru]

Originally Posted by VXEric

-snip-

Originally Posted by Tunafish

-snip-

Originally Posted by anjuna

-snip-.

Right, Air Intake codes haven't come back. However, the car stalled once on a cold start and drops very low and shudders when coasting to a stop, as if it's about to stall. Sometimes it will stall on a warm start too.

Got the code 2BEA Which is for lean fuel mixture.

I'm thinking this could also be caused by a faulty MAF so I'm leaning towards replacing it.

EDIT: Part ordered, hopefully that's it. Don't want to have to start dealing with fuel pumps.

[Null0Naru]

Further update: Issue is fixed.

Took it to a garage for a smoke test and a leak was found on one of the pipes coming from the turbo to the intercooler. Connection re-seated and the codes are gone and haven't come back.

Car's still adapting to having correct air readings but so far seems good.

[Null0Naru]

Update in case anyone comes across this thread.

This was a mixture of a boost leak from the turbo to intercooler as mentioned above, as well as a cracked PCV hose from the valve cover to the intake. After replacing the PCV hose the issue has gone away.

[PhillyM]

@Null0naru, bro I’m having a similar code on my car 108001: Intake air temperature sensor, electrical: short circuit to positive. Can you please let me know exactly what you did you get it fixed on your car? I would really appreciate it, I’ve been trying to get it figured out for months now with no luck and taking it to a few different shops.

[Turbz]

Last post from op was the solution mate.

This hose

https://www.mlperformance.co.uk/prod...caArxhEALw_wcB